Though BALF MMP-12 levels were altered amongst the study cohorts (1.7±0.1 ng/ml in control, 2.0±0.3 ng/ml in smokers, 11.8±4.7 ng/ml in emphysema; p<0.004 by Kruskal-Wallis test) (Figure 1C), only controls and emphysema subjects showed a significant intergroup difference. Here, MMP12 is linked to pulmonary emphysema.